kernel/linux.git/arch/s390/lib/delay.c, branch v7.0.10

s390: Explicitly include

2025-06-17T16:18:02+00:00

Explicitly include in files which contain an EXPORT_SYMBOL(). See commit a934a57a42f6 ("scripts/misc-check: check missing #include when W=1") for more details. Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/delay: sync comment within __delay() with reality

2022-08-30T20:00:33+00:00

The comment within __delay() is outdated and does not reflect anymore what the function is doing. Therefore replace the comment. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: remove invalid email address of Heiko Carstens

2022-02-06T22:31:29+00:00

Remove my old invalid email address which can be found in a couple of files. Instead of updating it, just remove my contact data completely from source files. We have git and other tools which allow to figure out who is responsible for what with recent contact data. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/delay: get rid of not needed header includes

2021-07-27T07:39:22+00:00

After all the changes to delay.c there are many includes which are not needed anymore. Get rid of them. Signed-off-by: Heiko Carstens

s390/delay: remove udelay_simple()

2020-12-16T13:55:49+00:00

udelay_simple() callers can make use of the now simplified udelay() implementation. No need to keep it. Signed-off-by: Heiko Carstens

s390/delay: simplify udelay

2020-12-16T13:55:49+00:00

udelay is implemented by using quite subtle details to make it possible to load an idle psw and waiting for an interrupt even in irq context or when interrupts are disabled. Also handling (or better: no handling) of softirqs is taken into account. All this is done to optimize for something which should in normal circumstances never happen: calling udelay to busy wait. Therefore get rid of the whole complexity and just busy loop like other architectures are doing it also. It could have been possible to use diag 0x44 instead of cpu_relax() in the busy loop, however we have seen too many bad things happen with diag 0x44 that it seems to be better to simply busy loop. Also note that with this new implementation kernel preemption does work when within the udelay loop. This did not work before. To get a feeling what the former code optimizes for: IPL'ing a kernel with 'defconfig' and afterwards compiling a kernel ends with a total of zero udelay calls. Signed-off-by: Heiko Carstens

Merge tag 's390-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2020-12-15T00:22:26+00:00

Pull s390 updates from Heiko Carstens: - Add support for the hugetlb_cma command line option to allocate gigantic hugepages using CMA - Add arch_get_random_long() support. - Add ap bus userspace notifications. - Increase default size of vmalloc area to 512GB and otherwise let it increase dynamically by the size of physical memory. This should fix all occurrences where the vmalloc area was not large enough. - Completely get rid of set_fs() (aka select SET_FS) and rework address space handling while doing that; making address space handling much more simple. - Reimplement getcpu vdso syscall in C. - Add support for extended SCLP responses (> 4k). This allows e.g. to handle also potential large system configurations. - Simplify KASAN by removing 3-level page table support and only supporting 4-levels from now on. - Improve debug-ability of the kernel decompressor code, which now prints also stack traces and symbols in case of problems to the console. - Remove more power management leftovers. - Other various fixes and improvements all over the place. * tag 's390-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (62 commits) s390/mm: add support to allocate gigantic hugepages using CMA s390/crypto: add arch_get_random_long() support s390/smp: perform initial CPU reset also for SMT siblings s390/mm: use invalid asce for user space when switching to init_mm s390/idle: fix accounting with machine checks s390/idle: add missing mt_cycles calculation s390/boot: add build-id to decompressor s390/kexec_file: fix diag308 subcode when loading crash kernel s390/cio: fix use-after-free in ccw_device_destroy_console s390/cio: remove pm support from ccw bus driver s390/cio: remove pm support from css-bus driver s390/cio: remove pm support from IO subchannel drivers s390/cio: remove pm support from chsc subchannel driver s390/vmur: remove unused pm related functions s390/tape: remove unsupported PM functions s390/cio: remove pm support from eadm-sch drivers s390: remove pm support from console drivers s390/dasd: remove unused pm related functions s390/zfcp: remove pm support from zfcp driver s390/ap: let bus_register() add the AP bus sysfs attributes ...

s390: fix irq state tracing

2020-12-02T17:17:50+00:00

With commit 58c644ba512c ("sched/idle: Fix arch_cpu_idle() vs tracing") common code calls arch_cpu_idle() with a lockdep state that tells irqs are on. This doesn't work very well for s390: psw_idle() will enable interrupts to wait for an interrupt. As soon as an interrupt occurs the interrupt handler will verify if the old context was psw_idle(). If that is the case the interrupt enablement bits in the old program status word will be cleared. A subsequent test in both the external as well as the io interrupt handler checks if in the old context interrupts were enabled. Due to the above patching of the old program status word it is assumed the old context had interrupts disabled, and therefore a call to TRACE_IRQS_OFF (aka trace_hardirqs_off_caller) is skipped. Which in turn makes lockdep incorrectly "think" that interrupts are enabled within the interrupt handler. Fix this by unconditionally calling TRACE_IRQS_OFF when entering interrupt handlers. Also call unconditionally TRACE_IRQS_ON when leaving interrupts handlers. This leaves the special psw_idle() case, which now returns with interrupts disabled, but has an "irqs on" lockdep state. So callers of psw_idle() must adjust the state on their own, if required. This is currently only __udelay_disabled(). Fixes: 58c644ba512c ("sched/idle: Fix arch_cpu_idle() vs tracing") Acked-by: Peter Zijlstra (Intel) Signed-off-by: Heiko Carstens

s390/udelay: make it work for the early code

2020-11-09T10:20:58+00:00

Currently udelay relies on working EXT interrupts handler, which is not the case during early startup. In such cases udelay_simple() has to be used instead. To avoid mistakes of calling udelay too early, which could happen from the common code as well - make udelay work for the early code by introducing static branch and redirecting all udelay calls to udelay_simple until EXT interrupts handler is fully initialized and async stack is allocated. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390: remove critical section cleanup from entry.S

2020-05-28T10:21:54+00:00

The current code is rather complex and caused a lot of subtle and hard to debug bugs in the past. Simplify the code by calling the system_call handler with interrupts disabled, save machine state, and re-enable them later. This requires significant changes to the machine check handling code as well. When the machine check interrupt arrived while being in kernel mode the new code will signal pending machine checks with a SIGP external call. When userspace was interrupted, the handler will switch to the kernel stack and directly execute s390_handle_mcck(). Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik